It is almost 90 degrees in Singapore, and the humidity is almost 90 percent. There are over 130 cases of the novel coronavirus there and the country's officials are hypervigilant, on the lookout for more. People in Singapore may not realize it, but the numbers of cases may remain small, not as much because of public health measures but because the heat and humidity may present a natural barrier to the spread of a respiratory virus.
By comparison, South Korea and New York currently have temperatures in the low 40s and the humidity is very low, conditions conducive to the spread of respiratory viruses. In South Korea, where over 200,000 people have been tested, there are over 6,000 confirmed cases and the coronavirus continues to spread.
The idea that many respiratory viruses (including influenza and other coronaviruses) follow a seasonal pattern is not a new one. It is based on the theory, believed by many virologists, that respiratory viruses travel farther on a cough or a sneeze in cold dry air than they do with hotter more humid weather where the water in the air causes the droplets to drop down to the ground.
As the coronavirus spreads through our communities, with more and more cases unearthed by expanded testing, we are entering a new phase of containment where we emphasize mitigating strategies, including more frequent and thorough handwashing, social distancing, better sleep and exercise, diet and lower stress, all intended to decrease our risks of catching this virus, especially problematic with no available vaccine.
We are beginning to practice cocooning, with more and more people staying at home, not attending events, not traveling, and if there is a personal concern about catching the virus, self-quarantining. This is all intended to decrease the amount of circulating virus so that someone who is more at risk (elderly or with severe chronic illness), doesn’t catch it.
At the same time that we try to stay ahead of this virus with these extreme measures – and we must prepare our hospitals for a potential surge of incoming patients – at the same time, we also hope that as the weather gets warmer and more humid, the virus itself will fade.
There is historical precedence for this hope, beyond the fact of the flu season, which generally peaks in January through March and then drops off by April.
Back in the fall of 2002, a new coronavirus emerged from China, and rapidly spread around the globe, infecting close to 8,000 people with close to 800 deaths. In April and May the world geared up for a large pandemic – that never came.
Many public health officials pride themselves on having imposed timely quarantines and closed schools and other places in Hong Kong, China, Singapore, Taiwan and Toronto, and the Centers for Disease Control and Prevention restricted travel to these areas.
Severe Acute Respiratory Syndrome was mostly gone by the following fall. I have always been more inclined to point to the weather for the drop-off, or as I wrote in "False Alarm; the Truth About the Epidemic of Fear" – the fact that the new virus wasn’t as contagious as we originally thought, but health officials at the time were patting themselves on the back for having squashed SARS.
The lesson from SARS is not that we shouldn’t have prepared, but that the hysteria and over-dramatizations and worst-case scenarios were completely unnecessary. Seventeen years later, we have forgotten this lesson, though we are still hoping for better weather to bail us out from a virus that is far more contagious, if less deadly, than was SARS.